Various populations have movement disorders. With an aging population comes the increased need for improved rehabilitation technologies for disabilities caused by brain and spinal cord injury, stroke and other neurological and orthopedic conditions. For stroke victims, intense physiotherapy is often required to regain and improve ambulatory and brain functions. Neurological conditions affecting walking and balance can also exist at any age, for example children with cerebral palsy suffer from a deficiency in their ability to control the movement of their bodies' center of mass. Patients suffering from brain and spinal cord injury, stroke or other neurological and orthopedic conditions, may benefit from mobility assistance and therapeutic devices. Current attempts at gait therapy improve function, but are labor intensive and limited by the demands and availability of physical therapists. The success of treatment is limited by the physical demands and availability of physical therapists. Robotic devices have been proposed for gait rehabilitation and other forms of movement training and rehabilitation and these can potentially reduce the physical burden on healthcare providers and the financial burden on patients.
The development of innovative movement training approaches for persons with movement disorders is important. Various patient groups demonstrate limited ability to bear body weight on their affected limbs during walking, e.g., stroke survivors with weakness on one side and kids with cerebral palsy. This results in shorter stance time on the affected side and asymmetric distribution of the ground reaction forces, affecting the overall gait symmetry. Such asymmetric gait patterns may be associated with higher energy costs and increased risks of fall, which, in turn, limits independence and quality of life of these subjects. Thus, symmetric weight bearing during walking may be important in gait rehabilitation.
Robotic rehabilitation devices can be used in physical therapy to offer more uniform training over an extended period of time and across different groups of patients. They can provide quantitative measures of the subject's performance and the required labor of physical therapists can be greatly reduced. Although various leg exoskeletons have been developed for gait training of neurologically impaired patients, many leg exoskeletons use links and mechanical joints placed in parallel with human limbs and joints, which adds extra weight and inertia to the human limbs and thereby changes the natural walking dynamics of the wearer. Furthermore, accurate alignment between the joints of the exoskeleton and the wearer is required, which may be difficult or impossible to accomplish due to the complex geometry of the human body.